Dual motor strapper

ABSTRACT

A pneumatic strapping tool for tensioning a strap around a load, adhering the strap onto itself, and cutting a feed end of the strap includes a piston, a weld motor operably connected to the piston and a vibrating weld element operably connected to the piston for contacting the strap and adhering the strap onto itself. A tensioning motor is configured for unidirectional rotation. A feed wheel is operably connected to the tensioning motor by a drive assembly to tension the strap prior to adhering the strap onto itself. A transmission cooperates with the drive assembly and is switchable between a first state in which the transmission engages the drive assembly to permit only one-way rotation of the drive assembly and a second state in which the transmission permits two-way rotation of the drive assembly. The strapping tool includes a self-contained pneumatic module that is removably mounted to a cylinder housing. The module includes a compressed gas inlet, a plurality of valves and passageways between the inlet and the valves to provide compressed gas to the cylinder housing, a pneumatic weld motor and the pneumatic tensioning motor. The module includes at least one timer for operation of the weld motor and for providing pressure to the cylinder. An articulating guide is disposed at the strap path and moves between an open path position when the tensioning motor housing is pivoted to the loading/unloading position and a closed path position when the tensioning motor housing is pivoted to the strap engaging position. The guide aligns the strap with a second strap to which the strap it is adhered and aligns the straps with the feed wheel and anvil.

BACKGROUND OF THE INVENTION

[0001] The present invention pertains to an improved tool for tighteninga strap around an object or load and adhering the strap onto itself.More particularly, the present invention is directed to a dual pneumaticmotor tool for tensioning a strap around a load and welding ormelt-adhering the strap onto itself.

[0002] Strapping tools are well-known in the art. These tools come in awide variety of types, from fully manual tools to automatic, table-toptools. These tools are generally specifically designed for use withmetal strapping or plastic/polymeric type strapping.

[0003] Typically, strappers for applying plastic or polymeric strappingmaterials are automatic table-top or hand-held devices. This isgenerally necessary in order to provide energy for adhering thestrapping material onto itself. Typically, the adhering function isprovided by melting or otherwise welding a section of the strappingmaterial onto itself. Such melting or welding operations are generallycarried out using ultrasonic or vibrational-type weld assemblies. Themovement or vibrational motion can be provided by electrical,electromechanical or fluid drive (hydraulic or pneumatic) systems.

[0004] In one exemplary tool, a pneumatic system is used to vibratecontacting interfacial surfaces of overlapping plastic strap portions.The tool includes a clamping member for anchoring a strap free endportion, and a rotatable feed wheel cooperating with an anvil foot toengage a feed strap portion that is tensioned about the load. A clutchengagably couples the feed wheel to a pneumatic motor which alsovibrates a jaw that welds the overlapping strap portions.

[0005] In this single motor arrangement, the motor stalls and tensioningstops at a specified strap tension. A pneumatically actuated ramdisengages the motor from the feed wheel and engages the feed wheelbreak that maintains feed wheel tension on the tensioned strap duringwelding. Such a tool is disclosed in U.S. Pat. No. 3,564,033 to Angarolaet al., which patent is assigned commonly herewith, and is incorporatedherein by reference. The actuated ram also moves the vibrating jaw intofrictional engagement with the overlapping strap portions. As thevibrating jaw moves toward the overlapping strap portions, a sheeringedge severs the upper strap and the overlapping strap portions aresubsequently welded together. The pressure is maintained on the weldedoverlapping strap portions for a cool down period to complete the weld.

[0006] Another exemplary tool, disclosed in U.S. Pat. No. 5,380,393 toDrabarek et al., also assigned commonly herewith and incorporated hereinby reference, discloses a strapping tool having a pneumatic circuit forautomatically controlling tool operation, including the timing andduration of strap welding and the cool down period. A pneumaticallyactuated ram extended after strap tensioning pivots a cam that moves avibrating weld plate into contact with overlapping strap portions toform the weld. Vibration of the weld plate terminates after a timeperiod controlled by the accumulation of air in a chamber. Air issubsequently bled from a cylinder that counter-pivots the ram to movethe welding plate away from the welded strap portions after the cooldown period.

[0007] As will be recognized by those skilled in the art, knownpneumatic strapping tools require many system components that increasethe size and weight of the tool. In addition, even though the pneumaticcircuit of the above-mentioned U.S. Pat. No. 5,380,393 automates manystrapping operations otherwise performed manually, controlling timing ofthe various tool operations as relatively and precise, and as a resultinconsistent strap tension and welds may result.

[0008] In operation of strapping tools, after tension is applied to thestrap, and prior to welding, the tension must be slightly released sothat the (welded) strap can be removed from the tool. Otherwise, thetension is typically so high and the foot or anvil is “pinched” sotightly between the strap and the load, that the tool is extremelydifficult to remove without damaging the strap.

[0009] In order to accomplish the release or backing-off of the tension,in many known strapping tools the tensioning motor is reversed orgearing is used to permit roll back of the feed wheel. As such, eitherthe feed (tensioning) motor must be a two-way motor or complex gearingis required to carry out the necessary functions of the tool.

[0010] Accordingly, there exists a need for a pneumatic strapping toolthat uses two pneumatic motors, one motor for tensioning or feedingstrap and another, separate motor for welding the strap material ontoitself. Desirably, such a tool uses one-way or unidirectional pneumaticmotors. Most desirably, such a tool has a self contained modularpneumatic member or module that includes pneumatically controlled timingcircuits and is readily installed onto and removed from the body andmotor portions of the tool. Even more desirably, such a toolincorporates guide elements to properly position and align the strapmaterial between the anvil and the feed wheel to assure optimal strapwelding.

BRIEF SUMMARY OF THE INVENTION

[0011] A pneumatic strapping tool tensions strap around a load, adheringthe strap onto itself, and cuts a feed end of the strap. The strapperincludes a piston, a weld motor operably connected to the piston and avibrating weld element operably connected to the piston for contactingthe strap and adhering the strap onto itself.

[0012] A tensioning motor is configured for unidirectional rotation. Afeed wheel rotates about a feed wheel shaft and is operably connected tothe tensioning motor by a drive assembly to tension the strap prior toadhering the strap onto itself. A transmission cooperates with the driveassembly. The transmission is switchable between a first state in whichthe transmission engages the drive assembly to permit only one-wayrotation of the drive assembly and a second state in which thetransmission permits two-way rotation of the drive assembly.

[0013] In a present embodiment, the drive assembly includes a driveshaft and the transmission includes a one-way bearing that bears on thedrive shaft. The one-way bearing permits one-way rotation of the driveshaft and prevents rotation of the drive shaft in an opposing direction.

[0014] The transmission can include a spring clutch engageable with thebearing. The spring clutch, in a first state binds on the bearing toprevent rotation of the bearing relative to the spring clutch. In asecond state, the spring clutch permits rotation of the bearing relativeto the spring clutch.

[0015] A release element cooperates with the spring clutch to move thespring clutch from the first state to the second state. The releaseelement can be configured as a collar fitted onto a portion of thebearing adjacent the spring clutch. The collar includes a fingerengageable with an end of the spring clutch to urge the spring clutch toa diameter larger than a diameter when the spring clutch binds on thebearing. The larger diameter state corresponds to the second state.

[0016] In a present strapping tool, the tensioning motor andtransmission are contained within a tensioning motor housing. A releasepin is disposed on the housing to traverse through the housing androtate the collar to engage the spring clutch.

[0017] The tool further includes a cylinder housing, a piston disposedwithin a cylinder in the cylinder housing, a pneumatic weld motoroperably connected to the piston and a vibrating weld element operablyconnected to the piston for contacting the strap and adhering the straponto itself.

[0018] To effect operation of the strapper, the tools includesself-contained pneumatic module that is removably mounted to thecylinder housing. The pneumatic module including a compressed gas inlet,a plurality of valves and passageways between the inlet and the valvesto provide compressed gas to the cylinder housing, the pneumatic weldmotor and the pneumatic tensioning motor.

[0019] The module also includes at least one timer for operation of theweld motor and for providing pressure to the cylinder. A part or portionof an accumulator for controlling timing of the weld motor is formed inthe module, and the other part or portion of the accumulator is formedin the cylinder housing.

[0020] The tool further includes a tensioning piston mounted in part inthe cylinder housing. The tensioning piston is actuated by compressedgas from the pneumatic module when the pneumatic tension motor isactuated. The tensioning piston acts against the tensioning motorhousing when the tool is operating in the tensioning mode.

[0021] The pneumatic module includes a tensioning motor valve forcontrolling compressed gas flow to the tensioning motor and a weld cyclevalve for controlling compressed gas flow to the weld motor and piston.The tensioning motor valve and the weld cycle valve are operableindependently of one another.

[0022] A pilot valve is configured to initiate and terminate flow ofcompressed gas to the tensioning motor valve and the weld cycle valve,that is, to the pneumatic module.

[0023] In a present embodiment, the module includes a tensioning motorvalve actuated by a tensioning motor valve switch, for providingcompressed gas flow to the pneumatic tensioning motor when thetensioning motor valve is in an on position. The module furtherincluding a weld cycle valve for providing compressed gas flow to thepneumatic weld motor and to the cylinder through a first pneumatictimer. Compressed gas flow is further provided to the accumulatorthrough a second timer. When compressed gas pressure in the accumulatorreaches a predetermined value, a pressure is applied to the pilot valveto close the pilot valve and to terminate compressed gas supply to theweld cycle valve. Pressure is vented from the cylinder through thesecond pneumatic timer to control cool down of the strap followingwelding.

[0024] In another aspect of the invention, an articulating guide isdisposed at the strap path. The guide pivots about the feed wheel shaftbetween an open path position and a closed path position.

[0025] In the open path position, that is when the tensioning motorhousing is pivoted to the loading/unloading position, the guide movesupwardly to permit inserting a strap between the feed wheel and anvil.In the closed path position, that is when the tensioning motor housingis pivoted to the strap engaging position, the guide blocks insertion ofthe strap between the feed wheel and the anvil and aligns the strap witha second strap to which the strap is to be adhered. The guide is furtherconfigured to align the strap and the second strap with the feed wheeland anvil for tensioning. To align the straps the guide includes adepending finger for movement in to and out of the strap path.

[0026] To effect articulation, the guide includes an elongated slot andthe strapping tool includes a pin extending therefrom for engaging theslot. The pin is fixed relative to the pivotal movement of thetensioning motor housing. The pin engages the slot to pivot the guidebetween the open path position and the closed path position. The fingercan be formed in a plane spaced inwardly of a plane of the guide to urgethe strap toward the feed wheel and anvil when the finger is in theclosed path position.

[0027] A feed wheel cover includes a notch formed therein for receivinga portion of the guide when the guide is pivoted to the closed pathposition. The notch maintains the guide laterally in place relative tothe feed wheel.

[0028] These and other features and advantages of the present inventionwill be apparent from the following detailed description, in conjunctionwith the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0029] The benefits and advantages of the present invention will becomemore readily apparent to those of ordinary skill in the relevant artafter reviewing the following detailed description and accompanyingdrawings, wherein:

[0030]FIG. 1 is a perspective view of a dual pneumatic motor strapperembodying the principles of the present invention, the tool being shownwith a strap material positioned in the tool, and showing the directionof movement of the material during tensioning;

[0031]FIG. 2 illustrates the tool positioned relative to a load beingstrapped and the direction of movement of the strap material duringtensioning;

[0032]FIG. 3 is a side view of the strapping tool shown in the operatingor engaged position in which the fed wheel engages the strap material;

[0033]FIG. 4 is a partial, enlarged view of the feed wheel and anvilwith strap material engaged therebetween, and showing the “roll-back” ofthe feed wheel following tensioning and welding, at release;

[0034]FIG. 5 is a side view of the strap positioned between the anviland feed wheel as illustrated in FIG. 4;

[0035]FIG. 6 is a side view of the strapping tool similar to FIG. 3, butshowing the tool in the release or loading/unloading position to loadstrap material into the strapper tool and to remove the strap materialafter it has been welded onto itself;

[0036]FIG. 7 is an exploded view of the strapping tool;

[0037]FIG. 8 is a partially exploded, partially cut-away view of thetensioning motor;

[0038]FIG. 9 is a cross-sectional view of the assembled motor takenalong 9-9 of FIG. 8;

[0039]FIG. 10 is a partial cross-sectional view of the motor taken alongline 10-10 of FIG. 9;

[0040]FIG. 11 is a partial view of the lower area of FIG. 10 showing therelease plunger engaging the motor inner sleeve to release the springclutch;

[0041]FIG. 12 is a cross-sectional view of the self contained pneumaticmodule taken along line 12-12 of FIG. 7; and

[0042]FIG. 13 is a schematic view of the self contained pneumaticmodule.

DETAILED DESCRIPTION OF THE INVENTION

[0043] While the present invention is susceptible of embodiment invarious forms, there is shown in the drawings and will hereinafter bedescribed a presently preferred embodiment with the understanding thatthe present disclosure is to be considered an exemplification of theinvention and is not intended to limit the invention to the specificembodiment illustrated.

[0044] It should be further understood that the title of this section ofthis specification, namely, “Detailed Description Of The Invention”,relates to a requirement of the United States Patent Office, and doesnot imply, nor should be inferred to limit the subject matter disclosedherein.

[0045] Referring now to the figures and in particular to FIGS. 1 and 2,there is shown a dual pneumatic motor strapper or strapping tool 10embodying the principles of the present invention. The tool 10 isconfigured to tension a strap S around a load L, weld the strap materialS onto itself and sever a feed end F of the strap S. For purposes of thepresent disclosure, the strap material S will be referred to as having afeed end F which is the supply end of the material and a free end Rwhich is that end of the material that is fed around the load L andreinserted into the strapping tool 10.

[0046] The tool 10 includes, generally, a body 12, a foot 14, atensioning motor 16 and housing 18, a weld motor 20, a cylinder housing22 and a pneumatic module 24. The tool 10 can include a handle 26 andgrip 28, such as those shown for ease of handling and use. The pneumaticmodule 24, as will be discussed in more detail below, is mounted to thecylinder housing 22 which is in turn mounted to the body 12 and providespneumatic pathways between the module 24, the cylinder housing 22 andthe tensioning and welding motors 16, 20 for introducing and venting acompressed gas, such as compressed air, to and from the motors 16, 20.The module 24 is readily mounted to and removed from the housing 22 by aplurality of fasteners 30 such as bolts and the like.

[0047] Referring now to FIG. 7, the welding motor 20 is mounted to thebody 12 in stationary relation so that the welding motor 20 and body 12are fixed relative to one another. A weld motor shaft 32 extending fromthe motor 20 engages an eccentric element 34. The eccentric element 34is positioned in an elongated opening 36 in an arm 38 that is operablyconnected at one end to a weld element 40 and at an opposing end to apiston 42. The piston 42 is positioned in the cylinder housing 22.

[0048] Upon actuation of the weld motor 20, the shaft 32 rotates whichin turn rotates the eccentric element 34. The eccentric 34 is fittedinto the elongated opening 36 so that as the motor 20 rotates, itimparts vibrational movement to the weld element 40. The upper and lowerstrap layers S_(U), S_(L) are positioned between the weld element 40 anda stationary weld pad 44 on the foot 14. The vibrational movement istransferred into the strap layers S_(U), S_(L) and welds the strap ontoitself The operation and construction of such vibrational weld elements40 and the various arrangements to impart vibrational energy will berecognized and understood by those skilled in the art and are within thescope and spirit of the present invention.

[0049] To assure that sufficient pressure is exerted by the weld element40, the piston receives compressed at the top of the piston 42 in thecylinder 46 when the tool 10 is in the welding cycle. The air forces thepiston 42 downwardly to assure that the proper force is exerted on thestrap S as the weld element 40 vibrates.

[0050] The foot 14 is likewise mounted to the body 12 so that foot 14and body 12 are stationary relative to one another. The foot 14 includesan anvil 48 against which the strap S is held for tensioning. As setforth above, the weld pad 44 is positioned on the foot 14 to maintain alower section of the strap S_(L) stationary as an upper section of strapS_(U) is vibrated to effect the weld.

[0051] The tensioning motor 16 is mounted in fixed relation to thetensioning motor housing 18 which is in turn pivotally mounted to thebody 12 by a pivot pin 50. The pin 50 permits the motor housing 18 topivot about an axis A₅₀. Gearing, indicated generally at 52, locatedwithin the housing 18 transfers the driving force from the motor 16 to afeed wheel shaft 54 on which a feed wheel 56 is mounted. As such, thefeed wheel 56 pivots along with the tensioning motor 16 and housing 18about the axis A₅₀.

[0052] The feed wheel 56 is positioned within a cover member 58. An end60 of the feed wheel shaft 54 is secured in a sleeve 62 in the cover 58.A plate 64 extends over the cover 58 to secure the cover 58 to the body12. In this manner the cover 58 pivots with the tensioning motor 16 andhousing 18 (and feed wheel 56) while the plate 64 remains fixed to thebody 12. The cover 58 prevents the feed wheel 56 from lateral movement.

[0053] The gearing 52 within the housing 18 for translating movement ofthe motor 16 to the feed wheel 56 includes a spiroid pinion (not shown)mounted to the motor shaft 68 and a spiroid gear (not shown) mounted tothe feed wheel shaft 54 to translate the rotational movement ninetydegrees from the motor 16 to the feed wheel 56. Such an arrangement, aswell as other arrangements will be readily recognized and appreciated bythose skilled in the art and are within the scope and spirit of thepresent invention.

[0054] The tensioning motor 16, as set forth above, is configured forone-way or unidirectional movement, as indicated by the rotational arrowat 72, when actuated by compressed air. It is, however, also configuredto permit a slight “slip” in an opposite direction to accommodate theroll back necessary for releasing tension in the strap S to permitremoving the tool 10 from the load L after the welding operation.

[0055] Referring now to FIGS. 8-11, unlike known strappers, the presentstrapper 10 uses a transmission assembly 74 that includes, generally, aone-way bearing 76, a spring clutch 78 and a release element 80, such asthe exemplary movable collar or ring to accomplish the roll back. Themotor shaft 68 is enveloped by or resides within the transmissionassembly 74. The one-way bearing 76 is positioned around the shaft 68and permits the shaft 68 to rotate in one direction, i.e., the drivingdirection 72 only. The bearing 76 includes a plurality of rollers 82within a sleeve 84. The sleeve 84 remains stationary while the rollers82 rotate to provide for smooth rotation of the shaft 68, and to preventlateral shaft 68 movement. Those skilled in the art will recognize andunderstand the construction of such a one-way bearing 76.

[0056] The wrap spring clutch 78 is fitted over a portion of the bearingsleeve 84. The spring clutch 78 is formed as a coil spring having firstand second ends 86, 88. The spring first end 86 is secured in a springseat 90. The spring second end 88 lies along the coil periphery. Thespring 78 has a relaxed state, that is a state in which the spring 78 isneither tensioned, compressed nor torqued (e.g., twisted). In therelaxed state, the spring 78 defines a diameter. When the spring 78 isin an other than relaxed state, such as when the spring 78 is torqued ortwisted, the diameter changes, for example, increases.

[0057] The spring clutch 78 is positioned over a portion of the bearingsleeve 84 to bind on the sleeve 84 when the spring 78 is in the relaxedstate, thus preventing movement of the bearing sleeve 84 relative to thespring 78. When the spring 78 is torqued or twisted, the diameterincreases to allow the sleeve 84 to “slip” relative to the spring 78. Itis this slippage that provides the roll back required to reduce thestrap S tension.

[0058] To accomplish the twisting of the spring 78, the transmissionincludes a collar 80 that is fitted onto the bearing sleeve 84 abuttingthe spring 78. The collar 80 includes a finger or projection 92extending longitudinally from an edge of the collar 80. While the collar80 abuts the end coil of the spring 78, the finger 92 is configured toabut the second end 88 of the spring 78. In this manner, when the collar80 is rotated, the finger 92 is urged against the end 88 of the coil totwist the spring 78. This, in turn, permits the bearing sleeve 84 (andthe shaft 68) to rotate backward relative to the spring 78.

[0059] The transmission 74 is contained within an outer sleeve 94 thatextends over the spring clutch 78 and collar 80 which are positionedover the bearing 76. A first end 96 of the outer sleeve 94 is open tothe motor 16 and an opposing or second end 98 of the outer sleeve 94 hasan opening 100 therein for the motor shaft 68 to pass through. The outersleeve 94 is positioned within the tensioning motor 18 housing andfixedly mounted therein by a plurality of fasteners (not shown) thatextend through the housing 18 and into the outer sleeve 94.

[0060] With reference now to FIGS. 10 and 11, in order to release thebearing 76 (i.e., torque the spring clutch 78), as set forth above, thecollar 80 must be urged or rotated slightly so that the finger 92contacts and moves the end 88 of the coil 78. To effect this slightrotation, the housing 18, outer sleeve 94 and collar 80 include openings104, 106 and 108, respectively, therein. The housing opening 104 andouter sleeve opening 106 are fully aligned with one another. The collaropening 108, however, is slightly out of alignment with the housing andsleeve openings 104, 106 when the spring 78 is in the relaxed state. Bymoving the collar opening 108 into alignment with the other openings104, 106, i.e., by slight rotation of the collar 80, the finger 92 urgesagainst the end 88 of the spring coil 78, to twist or torque the coil 78and release the bearing 76.

[0061] A release pin or plunger 110 and release handle 112 (FIG. 7) aremounted to the housing 18 such that the plunger 110 is disposed in thehousing and sleeve openings 104, 106 when it is depressed. The plunger110 is mounted for movement into the openings 104, 106, 108. The plunger110 includes a tapered head 114 that contacts the side of the collaropening 108 and rotates or cams against the collar opening 108 to effectrotation of the collar 80 and release of the bearing 76 and shaft 68.

[0062] Referring again to FIG. 7, the release handle 112 is mounted tothe housing 18, overlying the plunger 110 to maintain the plunger 110 inthe openings 104, 106, 108 and to provide leverage to force or urge theplunger 110 inward to contact and align the collar opening 108. Thehandle 112 is biased outwardly by, for example, the exemplary handlespring 116. The handle spring 116 bias is readily overcome by grippingthe handle 112, grip 28 and motor housing 18 and squeezing the handle112 inward. The plunger 110 is mounted to the handle 112 by a pin 118 orthe like so that as the handle 112 is released, it pulls the plunger 110out of the collar opening 108.

[0063] In addition, when the handle 112 is released, the force of thespring clutch 78 against the collar finger 92 rotates the collar opening108 out of alignment with the housing and sleeve openings 104, 106, thusfurther assisting in urging the plunger 110 outward. This action, i.e.,removing the plunger 110 from the collar opening 108, permits the springclutch 78 to return to the relaxed state, which in turn locks thebearing 76 within the spring clutch 78, preventing rearward rotation ofthe shaft 68 and feed wheel 56.

[0064] As set forth above, the tensioning motor 16, motor housing 18 andfeed wheel 56 pivot between an engaged position (shown in FIG. 3) inwhich the feed wheel 56 rests on the anvil 48 (during strappingoperations) and a loading/unloading position (FIG. 6) in which the feedwheel 56 is pivoted away from the anvil 48 to permit inserting orremoving the strap S material from between the feed wheel 56 and anvil48.

[0065] To assist in aligning the strapping material between the feedwheel 56 and anvil 48, the strapper 10 includes an articulating guide120. The guide 120 is configured to assure that the upper layer ofstrapping material S_(U) fully overlies the lower layer S_(L) ofmaterial, and further assures that both the upper and lower layersS_(U), S_(L) are positioned fully under the feed wheel 56 and above theanvil 48.

[0066] The guide 120 is mounted to the tool 10 by an opening 122 in theguide 120 through which the feed wheel shaft 54 traverses and a slottedopening 124 in the guide 120 through which a pivot pin 126 (extendingfrom the feed wheel cover plate 64) extends. Thus, as the tensioningmotor housing 18 (and thus the feed wheel 56) is pivoted to theloading/unloading position, the guide 120 articulates or pivots. The pin126 extending through the guide slot 124 articulates the guide 120 sothat an aligning finger 128 moves upwardly out of the strap entry way,as indicated at 130. When the motor housing 18 is released to return tothe engaged position, the guide 120 pivots downwardly to position thefinger 128 in the entry path 130 which aligns the upper layer of strapmaterial S_(U) on the lower layer of material SL. As best seen in FIG.7, the aligning finger 128 extends downwardly and inwardly to “push” anymisaligned strap between the feed wheel 56 and the anvil 48.

[0067] Referring now to FIGS. 7 and 12-13, the pneumatic module 24 isremovably mounted to the cylinder housing 22. The module 24 includes aplurality of components (e.g., switches, valves, accumulators) tocontrol the overall operation of the strapper 10. The module 24 isconfigured to readily mount to and be removed from the housing 22 by,for example, the exemplary bolts 30 (FIG. 1). In this manner, in theevent that maintenance is required on the pneumatic module 24, themodule 24 can be removed and a replacement module 24 can be readilyinstalled on the tool 10 for continued use.

[0068] Referring to FIG. 13, a pneumatic schematic is shown. Air entersthe tool 10 through a compressed air supply 134 and enters a pilot valve136. The pilot valve 136 is two position valve (on-off) that is biasedto the on position (as shown). The on position routes air to a juncture138 at which the air supply splits with one branch 140 routing air to atension motor valve 142 and the other branch 144 routing air to a weldcycle valve 146.

[0069] Depressing or actuating a tensioning motor switch 148 moves thetensioning motor valve 142 into the open position, routing air through avariable orifice 149 to the tensioning motor 16 and routing air to atensioning piston 150. The variable orifice 149 is adjustable to providecontrol of the tensioning motor 16 power output. (Note that thetensioning motor valve 142 is shown in the off or closed position.) Thepiston 150 extends downwardly from the cylinder housing 22 and applies aforce against the tensioning motor housing 18 when the tensioning motor16 is actuated. The piston 150 provides an assist to the spring force ofthe tool 10 to the engaged position. A spring 152 is positioned abovethe piston 150 to bias the piston 150 downwardly against the motorhousing 18. Releasing the tensioning motor switch 148 closes thetensioning motor valve 142, terminating the air feed to the tensioningmotor 16 and to the piston 150.

[0070] As set forth above, depressing the tensioning motor switch 148actuates the tension motor 16 which rotates, driving the drive shaft 68,which in turn rotates the feed wheel 56 to tension the strap S. When apredetermined tension is reached, the motor 16 stalls, and rotation ofthe feed wheel 56 ceases. Releasing the switch 148 merely stops the feedof air to the motor 16. Because of the transmission 74 configuration,i.e., the one-way bearing 76, the shaft 56 cannot rotate backward (thatis to relieve tension on the strap S), even though the force exerted bythe tensioned strap S tends to rotate the feed wheel 56 rearwardly.

[0071] A weld cycle switch 154 operates the weld cycle valve 146.Depressing the switch 154 moves the valve 146 to the on position. (Notethat the valve 146 is shown in the off or closed position.) The weldcycle valve 146 is a contact or maintain valve. In the on position, airis routed through the second line branch 144 to the valve 146. Airenters the valve 146 and is routed to the weld motor 20. A line tee 156from the weld motor line 144 is routed back to the weld cycle valve 146to “hold” the valve 146 in the on position. The valve 146 is biased tothe closed position, however, the air pressure “holding” the valve 146open is sufficiently high to overcome the spring force.

[0072] At the same time that air is routed to the weld motor 20, air isdirected to a volume chamber or accumulator 158, through a weld timer160 and check valve 162 for weld timing. The weld timer 160 is a checkvalve 164 in parallel with a restriction device such as the illustratedorifice 166. In this manner, air flow into the accumulator 158 isrestricted (and thus timed) in that flow through the orifice is limitedor restricted. A line 168 from the accumulator 158 is routed to thepilot valve 136, so that as the pressure in the accumulator 158increases, air flows to the pilot valve 136. When the air in theaccumulator 158 reaches a predetermined pressure, the pilot valve 136closes, thus stopping air flow to the weld cycle valve 146. This stopsoperation of the weld motor 20.

[0073] When air flow is terminated to the weld cycle valve 146, thepressure exerted to maintain the valve open (through line 156) alsodrops, and the valve 146 returns to the closed position by action of thebias.

[0074] Returning to the weld cycle, as air is provided to the weld motor20, air is also routed to the weld cylinder 46 (to the top of thepiston) to maintain pressure on the piston 42 (which assures thatsufficient pressure is applied by the weld element 40 on the strap S).The air is routed to the top of the weld cylinder 46 through a cool downtimer 170. As set forth above, after welding is complete, the strap Smust be allowed sufficient time to cool assure the integrity of theweld. Cool down is accomplish with pressure applied by the weld element40 on the strap S (pressure on the piston 42), without the vibrationalmotion of the element being imparted.

[0075] The cool down timer 170 maintains pressure on the piston 42without vibrational motion of the weld element 40. When the air to theweld motor is stopped, the weld element 40 ceases to vibrate. The airrouted to the top of the weld cylinder 46 is slowly vented from thecylinder 46 by a restricted vent path from the top of the cylinder 46.The cool down timer 170 is configured similar to the weld timer 160 andincludes a check valve 172 in parallel with a restriction device such asan orifice 174. In this manner, although the weld motor 20 has stopped,the pressure exerted by the (piston 42 and the) weld element 40 ismaintained and is slowly released by the timed venting from the cylinder46.

[0076] A cutter 176 is mounted to move downwardly into the strap upperlayer S_(U) along with the weld element 40. The cutter 176 is mounted tothe weld piston 42 by a spring 178 so that the force exerted on thestrap S is variable, to assure that the top layer of strap S_(U) is cut,but to also prevent cutting into lower layer of strap material S_(L).

[0077] Completing the pneumatic circuit, the accumulator 158 is ventedthrough the weld cycle valve 146 when the valve 146 is in the offposition. The vent is closed when the valve 146 is in the open position.Those skilled in the art will recognize and understand that the variousreferences to “lines”, “vent paths” and the like are provided by aplurality of openings formed, e.g., machined, in the module 24, as showngenerally in FIG. 12.

[0078] In operation, strap S is fed around the load L with the free endR positioned as the lower layer of strap S_(L) and the feed end Fpositioned as the upper layer of strap S_(U). The strap S is fed intothe strapper 10 with the strapper in the loading/unloading position (thetensioning motor housing 18 pulled upward). Both layers S_(U), S_(L) areproperly positioned in the strapper 10, and the motor housing 18 isreleased to move to the tool 10 to the engaged position. With the motorhousing 18 released, the guide 120 moves downwardly to align the strapmaterial layers S_(U), S_(L).

[0079] The tensioning motor switch 148 is depressed (moving thetensioning motor valve 142 to the on position) which actuates thetensioning motor 16 and the tensioning piston 150. The motor 16 rotateswhich in turn rotates the feed wheel 56 tensioning the strap S. When apredetermined tension is reached, the motor 16 stalls. The tensioningmotor switch 148 is then released which terminates air flow to the motor16 and to the piston 150. The strap S is, however, held securely by thefeed wheel 56 which is prevented from rotating rearwardly by thetransmission 74 (i.e., the one-way bearing 76).

[0080] The weld cycle switch 154 is then depressed to move the weldcycle valve 146 to the on position. As set forth above, this is acontact or maintain type switch. Compressed air is routed to the valve146 (bypassing the tensioning motor valve1 142), and is routed to theweld motor 20, to the weld cylinder 46 (through the cool down timer170), to the accumulator 158 (through the weld timer 160), and to thevalve 146 to maintain the valve 146 open. The weld piston 42 is forceddownwardly onto the strap S and the motor 20 is actuated to form theweld. At the same time, the strap upper layer S_(U) is cut by the cutter176 (which is moved into contact with the strap upper layer S_(U) by thepiston 42). As pressure in the accumulator 158 reaches a predeterminedvalue (by passage of air though the weld timer 160), the pilot valve 136closes thus terminating the flow of air to (and in turn from) the weldcycle valve 146.

[0081] When air flow is terminated from the weld cycle valve 146, themotor 20 stops and the valve 146 returns to the off position by actionof the bias 184 (spring). Weld cylinder 46 pressure slowly decreases byventing through the cool down timer 170. As pressure in the cylinder 46decreases, the piston spring 182 returns the piston 42 to the homeposition, moving the weld element 40 and cutter 176 from the strap S.

[0082] The release handle 112 is then gripped moving the plunger 110into the collar opening 108 to cam against the collar 80 and effectrelease of the drive shaft 68 and feed wheel 56. This reduces thetension in the strap S to permit removing the tool 10 from the weldedstrap S and load L.

[0083] All patents referred to herein, are hereby incorporated herein byreference, whether or not specifically do so within the text of thisdisclosure.

[0084] In the present disclosure, the words “a” or “an” are to be takento include both the singular and the plural. Conversely, any referenceto plural items shall, where appropriate, include the singular.

[0085] From the foregoing it will be observed that numerousmodifications and variations can be effectuated without departing fromthe true spirit and scope of the novel concepts of the presentinvention. It is to be understood that no limitation with respect to thespecific embodiments illustrated is intended or should be inferred. Thedisclosure is intended to cover by the appended claims all suchmodifications fall within the scope of the claims.

1-17. (Cancelled).
 18. A pneumatic strapping tool for tensioning a straparound a load, adhering the strap onto itself, and cutting a feed end ofthe strap, comprising: a body; a foot having an anvil and defining astrap path between the foot and the body; a weld motor mounted to thebody; a weld element operably connected to the weld motor for contactingthe strap and adhering the strap onto itself; a tensioning motor housingpivotally mounted to the body for pivoting between a loading/unloadingposition and a strap engaging position; a tensioning motor carried bythe tensioning motor housing, the tensioning motor configured forrotation; a feed wheel operably connected to the tensioning motor forrotation therewith and rotatable about a feed wheel shaft, the feedwheel being operably connected to the tensioning motor housing forpivoting therewith relative to the body and for tensioning a strappositioned between the feed wheel and the anvil; and an articulatingguide disposed at the strap path and movable between an open pathposition when the tensioning motor housing is pivoted to theloading/unloading position to permit inserting a strap between the feedwheel and anvil, and a closed path position when the tensioning motorhousing is pivoted to the strap engaging position to block insertion ofthe strap between the feed wheel and the anvil and to align the strapwith a second strap to which the strap is to be adhered, the guidefurther configured to align the strap and the second strap with the feedwheel and anvil.
 19. The strapping tool in accordance with claim 18wherein the guide is pivotable about the feed wheel shaft.
 20. Thestrapping tool in accordance with claim 18 wherein the guide includes afinger depending therefrom for movement in to and out of the strap path.21. The strapping tool in accordance with claim 19 wherein the guideincludes an elongated slot and wherein the strapping tool includes a pinextending therefrom, the pin being fixed relative to the pivotalmovement of the tensioning motor housing, the pin engaging the slot topivot the guide between the open path position and the closed pathposition.
 22. The strapping tool in accordance with claim 21 including afeed wheel cover, the feed wheel cover having a notch formed therein forreceiving a portion of the guide when the guide is pivoted to the closedpath position.
 23. The strapping tool in accordance with claim 20wherein the finger is formed in a plane spaced inwardly of a plane ofthe guide to urge the strap toward the feed wheel and anvil when thefinger contacts the strap.